Rafael Nadal has withdrawn from the season-ending ATP Finals due to a persistent abdominal injury and will take the time off to have ankle surgery.
The Spaniard lost his place as world number one last week when injury forced him to pull out of the Paris Masters, with Novak Djokovic moving to the top of the rankings.
And Nadal will not get the opportunity to end the year on a high as he will not play in London, citing both last week's abdominal issue and a long-standing ankle problem for his absence.
"It has been a complicated year - very good at the tennis level when I have been able to play and, at the same time, very bad as far as injuries are concerned," Nadal wrote on Twitter.
"I have done everything possible to get to the end of the season in good condition, both to Paris and to London, doing things well, and I really wanted to play.
"Unfortunately, I had the abdominal problem in Paris last week and I also have a free body in the ankle joint that has to be removed in the operating room [on Monday].
"We had detected it for some time and it occasionally bothered me. However, since the problem in the abdominal muscle also prevents me from playing in London, we are taking the time to remove the free body and avoid future problems.
"This way I hope to be in full condition for next season."
Nadal has not featured on the ATP World Tour since retiring in the semi-finals of the US Open in September, also suffering this year with hip and knee problems.
The 32-year-old won the French Open - his 17th grand slam title - but he competed in just three hard-court tournaments in 2018, winning the Rogers Cup while retiring at both the Australian Open and at Flushing Meadows.
Djokovic is set to end the year as number one, having enjoyed a sensational run of results that saw him triumph at Wimbledon and the US Open.
|Nowell an option for England at flanker, reveals Jones|
|Pellegrini: Arnautovic available for the right price|
|Knicks throw away 19-point lead and lose on last-second goaltending call|
|Tebow invited back to Mets´ major league spring training|
|Canelo and Jacobs agree unification fight|
|Barcelona 3 Levante 0 (4-2 agg): Dembele at the double as Barca advance|
|Levante to lodge complaint over Barcelona Copa selection|
|Kanter´s London absence ´very unfortunate´, says NBA commissioner|
|NBA could swap London for Paris in 2020|
|Spurs coach Popovich uncertain if he will return next season|
|Pistons´ Griffin fined for verbal abuse of official|
|Everton do not have financial conditions to enter transfer market - Silva|
|Andy Cole joins Sol Campbell´s coaching staff at Macclesfield|
|Atletico confirm Saul has thigh injury|
|Wood replaces injured Stone in England squad|
|Lebanon 4 North Korea 1: Disciplinary record cruelly denies Radulovic´s men|
|Saudi Arabia 0 Qatar 2: In-form Ali bags brace as Qatar top group|
|Robertson signs new Liverpool deal|
|Vunipola backs Farrell to thrive in solo leadership role|
|People don´t know what´s going on behind the scenes - Mourinho defends United stint|
|Indefatigable Muguruza knocks out Konta at 3:12am|
|Serena coasts, difficulties for Halep and Muguruza´s marathon|
|Lowry retains Abu Dhabi lead|
|Djokovic battles past Tsonga, young guns flourish|
|Louisville airport to be renamed in Muhammad Ali´s honour|
|Emery not thinking about Ozil speculation|
|Sri Lanka hopeful over Kusal Mendis finger injury|
|Oman 3 Turkmenistan 1: Last-gasp Al-Musallami guarantees progression|
|Emery wants Cech to end career ´in a good moment´|
|Japan 2 Uzbekistan 1: Shiotani stunner seals comeback and top spot|
|Calhanoglu deal ´financially impossible´ for Leipzig|
|Not seen at Aus Open since Nadal, Djokovic and Murray in 2009 – ´Next Gen´ make move|
|Martial: Solskjaer lets me express myself|
|Djokovic sees off Tsonga to reach third round|
|Returning Cousins calls Warriors ´the most hated team in sports´|
|Halep injury ´nothing dangerous´|
|Warner picks up elbow injury in Bangladesh|
|Mkhitaryan returning to Arsenal training next week|
|Leeds United pounce for Real Madrid goalkeeper Casilla|
|Watson lights up Gabba before power cut forces abandonment|
|Superb Serena blows Bouchard away|
|Tevez, Hulk, Oscar, Lavezzi - how the CSL stars Dembele is following to China fared|
|Thiem retires from Australian Open|
|Osaka ´not telling´ when it comes to injury niggle|
|Fabinho enjoying Klopp´s management style|
|Halep battles past Kenin in Melbourne|
|Hartley to miss England´s Six Nations opener|
|Dembele departs Spurs for Guangzhou R&F|
|Nacho convinced Isco remains important to Real Madrid|
|Warriors star Curry sets NBA record|
|Raonic survives four-hour marathon against Wawrinka|
|Osaka powers through to Aus Open third round|
|Irving dominates in Celtics´ win over Raptors|
|Irving called LeBron this week to apologise|
|Ajax star De Jong wants to resolve future ´quickly´|
|Payton on Rams CB Peters: I have great respect for him|
|Rockets star Harden matches Chamberlain with historic performances|
|Nishikori survives Karlovic test in Melbourne|
|Vieira reunion felt really weird - Henry|
|´#BetAgainstUs´ - Edelman and Pats embracing underdog status|
|Van der Vaart: Isco the best player in the world|
|I haven´t seen Guardiola or Klopp do that – Lampard unhappy with Bielsa|
|Real Madrid always play to win, insists Casemiro|
|Royals pitcher Skoglund suspended for 80 games after testing positive for PEDs|
|Ronaldo and Juve celebrate Supercoppa Italiana title with Mayweather|
|We are not going to talk about Morata - Simeone reluctant to discuss striker|
|Madrid weak in Leganes loss, says Solari|
|Bologna and Banvit seal Champions League play-off spots|
|LeBron James to miss Thunder & Rockets games but nearing practice return|
|Leganes 1 Real Madrid 0 (1-3 agg): Isco starts as Solari´s side go through despite defeat|